Study of alloCART-19 Cell Therapy in Pediatric Patients With Relapsed/Refractory B-Cell Acute Lymphoblastic Leukemia

Inclusion Criteria * Signed informed consent and assent forms if applicable must be obtained prior to the start of any research procedure * Age 1 year at the time of screening to age 18 years at the time of initial diagnosis * Relapsed/refractory pediatric ALL that meet one of the following conditions: 1. Incomplete patients with conventional chemotherapy regimens, or primary refractory patients who failed to complete remission with 2 courses of standard chemotherapy regimen, or did not achieve complete remission after first-line or multi-line salvage chemotherapy 2. Early recurrence after complete remission (\< 12 months) or late recurrence after complete remission (≥ 12 months) and chemotherapy was not completely relieved by the standardized two course induction regimens 3. Recurrence after autologous or allogeneic hematopoietic stem cell transplantation * Patients who are Philadelphia chromosome-positive (Ph+) are eligible if they have failed at least 2 lines of chemotherapy and have failed two lines of TKI therapy or if TKI therapy is contraindicated. * For relapsed patients, CD19 tumor expression demonstrated in bone marrow or peripheral blood by flow cytometry within 3 months of study entry * Karnofsky performance status of \> 60 at screening * During the screening period and within 10 days of treatment, adequate organ function defined as: 1. Renal Function: serum creatinine ≤ 2 x ULN 2. Liver Function: ALT and/or AST ≤ 10 x ULN (depending on age), bilirubin ≤ 5 x ULN 3. Pulmonary Function: oxygen saturation ≥ 91% 4. Heart Function: echocardiogram (ECHO): left ventricular ejection fraction (LVEF) ≥ 45% * Bone marrow with ≥ 5% lymphoblasts by morphologic assessment at screening or immunological/molecular biological results with persistent MRD * Female subjects of childbearing age must have a negative serum or urine pregnancy test during the screening period and agree to take effective contraceptive measures during the trial period until the last follow-up Exclusion Criteria * Pregnant or lactating women * Unable to tolerate venipuncture * Prior history of: 1. Allogeneic cell therapy (including hematopoietic stem cell transplantation) within 6 weeks of alloCART-19 infusion 2. Any live vaccine within 4 weeks of alloCART-19 infusion and/or plan to receive live vaccine after enrollment 3. Immunosuppressants for GvHD treatment within 4 weeks of alloCART-19 infusion 4. Systemic corticosteroid treatment at doses greater than 5 mg/day prednisone\*3 days (or equivalent corticosteroids) within 72 hours prior to alloCART-19 treatment 5. Before receiving alloCART-19 treatment, had received the following anti-neoplastic therapies: Tyrosine kinase inhibitors and hydroxyurea within 72 hours; Vincristine, 6-mercaptopurine, 6-thioguanine, methotrexate \< 25 mg/m2, cytosine arabinoside \< 100 mg/m2/day, or asparaginase (non-pegylated) within 1-week; Pegylated-asparaginase within 4 weeks; Central nervous system disease prophylaxis (e.g. intrathecal methotrexate) within 1 week; Investigational drug treatment within 4 weeks 6. Had received the following anti-neoplastic radiotherapy before receiving alloCART-19 treatment: Radiotherapy for non-CNS sites within 2 weeks; Radiotherapy for the CNS site within 8 weeks * Have the following medical history: 1. Grade 2 to 4 acute or extensive chronic graft-versus-host disease (GVHD) 2. Isolated extramedullary disease recurrence (e.g. central nervous system and testis) 3. Previous or active central nervous system (CNS) diseases such as seizures, cerebral ischemia/bleeding, dementia, cerebellar disease or any autoimmune disease involving CNS 4. Previous malignant tumors (excluding curative trends and inactive skin cancer in situ or cervical cancer) 5. Genetic syndromes associated with bone marrow failure states: such as Fanconi anemia, Kostmann syndrome, Shwachman syndrome or any other known bone marrow failure syndrome (excluding Down syndrome) 6. Active or latent hepatitis B or active hepatitis C (test within 8 weeks of screening period) 7. History of HIV, or HIV-positive test within 8 weeks of screening period 8. Any uncontrolled serious infection during the screening period 9. Severe, poorly controlled concomitant diseases such as, but not limited to, nervous system, kidney, liver, endocrine or gastrointestinal disorders that may be deemed by the investigator to interfere with the inclusion of the subject in the study. 10. Any clinical abnormalities including but not limited to the nervous system, cardiovascular system, blood and lymphatic system, immune system, kidney, liver, gastrointestinal tract, respiratory system, metabolism and bones that may be deemed by the investigator to interfere with the inclusion of a subject in the study. * The following treatments and/or medications must be excluded: 1. Simultaneous application of other anti-neoplastic drugs, including traditional Chinese herbal medicines 2. Drugs that prolong the QT interval (including Ia and III antiarrhythmic drugs) 3. Daily oxygen therapy 4. long-term use of corticosteroids (except for inhaled and topical use) * Any circumstance or condition that in the judgement of the investigator may interfere with the subject's participation in the trial.